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Diffstat (limited to 'ext/pdo_sqlite/sqlite/src/where.c')
| -rw-r--r-- | ext/pdo_sqlite/sqlite/src/where.c | 2052 |
1 files changed, 0 insertions, 2052 deletions
diff --git a/ext/pdo_sqlite/sqlite/src/where.c b/ext/pdo_sqlite/sqlite/src/where.c deleted file mode 100644 index d057acd0fe..0000000000 --- a/ext/pdo_sqlite/sqlite/src/where.c +++ /dev/null @@ -1,2052 +0,0 @@ -/* -** 2001 September 15 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** May you find forgiveness for yourself and forgive others. -** May you share freely, never taking more than you give. -** -************************************************************************* -** This module contains C code that generates VDBE code used to process -** the WHERE clause of SQL statements. This module is reponsible for -** generating the code that loops through a table looking for applicable -** rows. Indices are selected and used to speed the search when doing -** so is applicable. Because this module is responsible for selecting -** indices, you might also think of this module as the "query optimizer". -** -** $Id$ -*/ -#include "sqliteInt.h" - -/* -** The number of bits in a Bitmask. "BMS" means "BitMask Size". -*/ -#define BMS (sizeof(Bitmask)*8) - -/* -** Determine the number of elements in an array. -*/ -#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0])) - -/* -** Trace output macros -*/ -#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG) -int sqlite3_where_trace = 0; -# define TRACE(X) if(sqlite3_where_trace) sqlite3DebugPrintf X -#else -# define TRACE(X) -#endif - -/* Forward reference -*/ -typedef struct WhereClause WhereClause; - -/* -** The query generator uses an array of instances of this structure to -** help it analyze the subexpressions of the WHERE clause. Each WHERE -** clause subexpression is separated from the others by an AND operator. -** -** All WhereTerms are collected into a single WhereClause structure. -** The following identity holds: -** -** WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm -** -** When a term is of the form: -** -** X <op> <expr> -** -** where X is a column name and <op> is one of certain operators, -** then WhereTerm.leftCursor and WhereTerm.leftColumn record the -** cursor number and column number for X. WhereTerm.operator records -** the <op> using a bitmask encoding defined by WO_xxx below. The -** use of a bitmask encoding for the operator allows us to search -** quickly for terms that match any of several different operators. -** -** prereqRight and prereqAll record sets of cursor numbers, -** but they do so indirectly. A single ExprMaskSet structure translates -** cursor number into bits and the translated bit is stored in the prereq -** fields. The translation is used in order to maximize the number of -** bits that will fit in a Bitmask. The VDBE cursor numbers might be -** spread out over the non-negative integers. For example, the cursor -** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45. The ExprMaskSet -** translates these sparse cursor numbers into consecutive integers -** beginning with 0 in order to make the best possible use of the available -** bits in the Bitmask. So, in the example above, the cursor numbers -** would be mapped into integers 0 through 7. -*/ -typedef struct WhereTerm WhereTerm; -struct WhereTerm { - Expr *pExpr; /* Pointer to the subexpression */ - i16 iParent; /* Disable pWC->a[iParent] when this term disabled */ - i16 leftCursor; /* Cursor number of X in "X <op> <expr>" */ - i16 leftColumn; /* Column number of X in "X <op> <expr>" */ - u16 operator; /* A WO_xx value describing <op> */ - u8 flags; /* Bit flags. See below */ - u8 nChild; /* Number of children that must disable us */ - WhereClause *pWC; /* The clause this term is part of */ - Bitmask prereqRight; /* Bitmask of tables used by pRight */ - Bitmask prereqAll; /* Bitmask of tables referenced by p */ -}; - -/* -** Allowed values of WhereTerm.flags -*/ -#define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(pExpr) */ -#define TERM_VIRTUAL 0x02 /* Added by the optimizer. Do not code */ -#define TERM_CODED 0x04 /* This term is already coded */ -#define TERM_COPIED 0x08 /* Has a child */ -#define TERM_OR_OK 0x10 /* Used during OR-clause processing */ - -/* -** An instance of the following structure holds all information about a -** WHERE clause. Mostly this is a container for one or more WhereTerms. -*/ -struct WhereClause { - Parse *pParse; /* The parser context */ - int nTerm; /* Number of terms */ - int nSlot; /* Number of entries in a[] */ - WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */ - WhereTerm aStatic[10]; /* Initial static space for a[] */ -}; - -/* -** An instance of the following structure keeps track of a mapping -** between VDBE cursor numbers and bits of the bitmasks in WhereTerm. -** -** The VDBE cursor numbers are small integers contained in -** SrcList_item.iCursor and Expr.iTable fields. For any given WHERE -** clause, the cursor numbers might not begin with 0 and they might -** contain gaps in the numbering sequence. But we want to make maximum -** use of the bits in our bitmasks. This structure provides a mapping -** from the sparse cursor numbers into consecutive integers beginning -** with 0. -** -** If ExprMaskSet.ix[A]==B it means that The A-th bit of a Bitmask -** corresponds VDBE cursor number B. The A-th bit of a bitmask is 1<<A. -** -** For example, if the WHERE clause expression used these VDBE -** cursors: 4, 5, 8, 29, 57, 73. Then the ExprMaskSet structure -** would map those cursor numbers into bits 0 through 5. -** -** Note that the mapping is not necessarily ordered. In the example -** above, the mapping might go like this: 4->3, 5->1, 8->2, 29->0, -** 57->5, 73->4. Or one of 719 other combinations might be used. It -** does not really matter. What is important is that sparse cursor -** numbers all get mapped into bit numbers that begin with 0 and contain -** no gaps. -*/ -typedef struct ExprMaskSet ExprMaskSet; -struct ExprMaskSet { - int n; /* Number of assigned cursor values */ - int ix[sizeof(Bitmask)*8]; /* Cursor assigned to each bit */ -}; - - -/* -** Bitmasks for the operators that indices are able to exploit. An -** OR-ed combination of these values can be used when searching for -** terms in the where clause. -*/ -#define WO_IN 1 -#define WO_EQ 2 -#define WO_LT (WO_EQ<<(TK_LT-TK_EQ)) -#define WO_LE (WO_EQ<<(TK_LE-TK_EQ)) -#define WO_GT (WO_EQ<<(TK_GT-TK_EQ)) -#define WO_GE (WO_EQ<<(TK_GE-TK_EQ)) - -/* -** Value for flags returned by bestIndex() -*/ -#define WHERE_ROWID_EQ 0x0001 /* rowid=EXPR or rowid IN (...) */ -#define WHERE_ROWID_RANGE 0x0002 /* rowid<EXPR and/or rowid>EXPR */ -#define WHERE_COLUMN_EQ 0x0010 /* x=EXPR or x IN (...) */ -#define WHERE_COLUMN_RANGE 0x0020 /* x<EXPR and/or x>EXPR */ -#define WHERE_COLUMN_IN 0x0040 /* x IN (...) */ -#define WHERE_TOP_LIMIT 0x0100 /* x<EXPR or x<=EXPR constraint */ -#define WHERE_BTM_LIMIT 0x0200 /* x>EXPR or x>=EXPR constraint */ -#define WHERE_IDX_ONLY 0x0800 /* Use index only - omit table */ -#define WHERE_ORDERBY 0x1000 /* Output will appear in correct order */ -#define WHERE_REVERSE 0x2000 /* Scan in reverse order */ -#define WHERE_UNIQUE 0x4000 /* Selects no more than one row */ - -/* -** Initialize a preallocated WhereClause structure. -*/ -static void whereClauseInit(WhereClause *pWC, Parse *pParse){ - pWC->pParse = pParse; - pWC->nTerm = 0; - pWC->nSlot = ARRAYSIZE(pWC->aStatic); - pWC->a = pWC->aStatic; -} - -/* -** Deallocate a WhereClause structure. The WhereClause structure -** itself is not freed. This routine is the inverse of whereClauseInit(). -*/ -static void whereClauseClear(WhereClause *pWC){ - int i; - WhereTerm *a; - for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){ - if( a->flags & TERM_DYNAMIC ){ - sqlite3ExprDelete(a->pExpr); - } - } - if( pWC->a!=pWC->aStatic ){ - sqliteFree(pWC->a); - } -} - -/* -** Add a new entries to the WhereClause structure. Increase the allocated -** space as necessary. -** -** WARNING: This routine might reallocate the space used to store -** WhereTerms. All pointers to WhereTerms should be invalided after -** calling this routine. Such pointers may be reinitialized by referencing -** the pWC->a[] array. -*/ -static int whereClauseInsert(WhereClause *pWC, Expr *p, int flags){ - WhereTerm *pTerm; - int idx; - if( pWC->nTerm>=pWC->nSlot ){ - WhereTerm *pOld = pWC->a; - pWC->a = sqliteMalloc( sizeof(pWC->a[0])*pWC->nSlot*2 ); - if( pWC->a==0 ) return 0; - memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm); - if( pOld!=pWC->aStatic ){ - sqliteFree(pOld); - } - pWC->nSlot *= 2; - } - pTerm = &pWC->a[idx = pWC->nTerm]; - pWC->nTerm++; - pTerm->pExpr = p; - pTerm->flags = flags; - pTerm->pWC = pWC; - pTerm->iParent = -1; - return idx; -} - -/* -** This routine identifies subexpressions in the WHERE clause where -** each subexpression is separated by the AND operator or some other -** operator specified in the op parameter. The WhereClause structure -** is filled with pointers to subexpressions. For example: -** -** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22) -** \________/ \_______________/ \________________/ -** slot[0] slot[1] slot[2] -** -** The original WHERE clause in pExpr is unaltered. All this routine -** does is make slot[] entries point to substructure within pExpr. -** -** In the previous sentence and in the diagram, "slot[]" refers to -** the WhereClause.a[] array. This array grows as needed to contain -** all terms of the WHERE clause. -*/ -static void whereSplit(WhereClause *pWC, Expr *pExpr, int op){ - if( pExpr==0 ) return; - if( pExpr->op!=op ){ - whereClauseInsert(pWC, pExpr, 0); - }else{ - whereSplit(pWC, pExpr->pLeft, op); - whereSplit(pWC, pExpr->pRight, op); - } -} - -/* -** Initialize an expression mask set -*/ -#define initMaskSet(P) memset(P, 0, sizeof(*P)) - -/* -** Return the bitmask for the given cursor number. Return 0 if -** iCursor is not in the set. -*/ -static Bitmask getMask(ExprMaskSet *pMaskSet, int iCursor){ - int i; - for(i=0; i<pMaskSet->n; i++){ - if( pMaskSet->ix[i]==iCursor ){ - return ((Bitmask)1)<<i; - } - } - return 0; -} - -/* -** Create a new mask for cursor iCursor. -** -** There is one cursor per table in the FROM clause. The number of -** tables in the FROM clause is limited by a test early in the -** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[] -** array will never overflow. -*/ -static void createMask(ExprMaskSet *pMaskSet, int iCursor){ - assert( pMaskSet->n < ARRAYSIZE(pMaskSet->ix) ); - pMaskSet->ix[pMaskSet->n++] = iCursor; -} - -/* -** This routine walks (recursively) an expression tree and generates -** a bitmask indicating which tables are used in that expression -** tree. -** -** In order for this routine to work, the calling function must have -** previously invoked sqlite3ExprResolveNames() on the expression. See -** the header comment on that routine for additional information. -** The sqlite3ExprResolveNames() routines looks for column names and -** sets their opcodes to TK_COLUMN and their Expr.iTable fields to -** the VDBE cursor number of the table. This routine just has to -** translate the cursor numbers into bitmask values and OR all -** the bitmasks together. -*/ -static Bitmask exprListTableUsage(ExprMaskSet*, ExprList*); -static Bitmask exprSelectTableUsage(ExprMaskSet*, Select*); -static Bitmask exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){ - Bitmask mask = 0; - if( p==0 ) return 0; - if( p->op==TK_COLUMN ){ - mask = getMask(pMaskSet, p->iTable); - return mask; - } - mask = exprTableUsage(pMaskSet, p->pRight); - mask |= exprTableUsage(pMaskSet, p->pLeft); - mask |= exprListTableUsage(pMaskSet, p->pList); - mask |= exprSelectTableUsage(pMaskSet, p->pSelect); - return mask; -} -static Bitmask exprListTableUsage(ExprMaskSet *pMaskSet, ExprList *pList){ - int i; - Bitmask mask = 0; - if( pList ){ - for(i=0; i<pList->nExpr; i++){ - mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr); - } - } - return mask; -} -static Bitmask exprSelectTableUsage(ExprMaskSet *pMaskSet, Select *pS){ - Bitmask mask; - if( pS==0 ){ - mask = 0; - }else{ - mask = exprListTableUsage(pMaskSet, pS->pEList); - mask |= exprListTableUsage(pMaskSet, pS->pGroupBy); - mask |= exprListTableUsage(pMaskSet, pS->pOrderBy); - mask |= exprTableUsage(pMaskSet, pS->pWhere); - mask |= exprTableUsage(pMaskSet, pS->pHaving); - } - return mask; -} - -/* -** Return TRUE if the given operator is one of the operators that is -** allowed for an indexable WHERE clause term. The allowed operators are -** "=", "<", ">", "<=", ">=", and "IN". -*/ -static int allowedOp(int op){ - assert( TK_GT>TK_EQ && TK_GT<TK_GE ); - assert( TK_LT>TK_EQ && TK_LT<TK_GE ); - assert( TK_LE>TK_EQ && TK_LE<TK_GE ); - assert( TK_GE==TK_EQ+4 ); - return op==TK_IN || (op>=TK_EQ && op<=TK_GE); -} - -/* -** Swap two objects of type T. -*/ -#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;} - -/* -** Commute a comparision operator. Expressions of the form "X op Y" -** are converted into "Y op X". -*/ -static void exprCommute(Expr *pExpr){ - assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN ); - SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl); - SWAP(Expr*,pExpr->pRight,pExpr->pLeft); - if( pExpr->op>=TK_GT ){ - assert( TK_LT==TK_GT+2 ); - assert( TK_GE==TK_LE+2 ); - assert( TK_GT>TK_EQ ); - assert( TK_GT<TK_LE ); - assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE ); - pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT; - } -} - -/* -** Translate from TK_xx operator to WO_xx bitmask. -*/ -static int operatorMask(int op){ - int c; - assert( allowedOp(op) ); - if( op==TK_IN ){ - c = WO_IN; - }else{ - c = WO_EQ<<(op-TK_EQ); - } - assert( op!=TK_IN || c==WO_IN ); - assert( op!=TK_EQ || c==WO_EQ ); - assert( op!=TK_LT || c==WO_LT ); - assert( op!=TK_LE || c==WO_LE ); - assert( op!=TK_GT || c==WO_GT ); - assert( op!=TK_GE || c==WO_GE ); - return c; -} - -/* -** Search for a term in the WHERE clause that is of the form "X <op> <expr>" -** where X is a reference to the iColumn of table iCur and <op> is one of -** the WO_xx operator codes specified by the op parameter. -** Return a pointer to the term. Return 0 if not found. -*/ -static WhereTerm *findTerm( - WhereClause *pWC, /* The WHERE clause to be searched */ - int iCur, /* Cursor number of LHS */ - int iColumn, /* Column number of LHS */ - Bitmask notReady, /* RHS must not overlap with this mask */ - u16 op, /* Mask of WO_xx values describing operator */ - Index *pIdx /* Must be compatible with this index, if not NULL */ -){ - WhereTerm *pTerm; - int k; - for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){ - if( pTerm->leftCursor==iCur - && (pTerm->prereqRight & notReady)==0 - && pTerm->leftColumn==iColumn - && (pTerm->operator & op)!=0 - ){ - if( iCur>=0 && pIdx ){ - Expr *pX = pTerm->pExpr; - CollSeq *pColl; - char idxaff; - int k; - Parse *pParse = pWC->pParse; - - idxaff = pIdx->pTable->aCol[iColumn].affinity; - if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue; - pColl = sqlite3ExprCollSeq(pParse, pX->pLeft); - if( !pColl ){ - if( pX->pRight ){ - pColl = sqlite3ExprCollSeq(pParse, pX->pRight); - } - if( !pColl ){ - pColl = pParse->db->pDfltColl; - } - } - for(k=0; k<pIdx->nColumn && pIdx->aiColumn[k]!=iColumn; k++){} - assert( k<pIdx->nColumn ); - if( pColl!=pIdx->keyInfo.aColl[k] ) continue; - } - return pTerm; - } - } - return 0; -} - -/* Forward reference */ -static void exprAnalyze(SrcList*, ExprMaskSet*, WhereClause*, int); - -/* -** Call exprAnalyze on all terms in a WHERE clause. -** -** -*/ -static void exprAnalyzeAll( - SrcList *pTabList, /* the FROM clause */ - ExprMaskSet *pMaskSet, /* table masks */ - WhereClause *pWC /* the WHERE clause to be analyzed */ -){ - int i; - for(i=pWC->nTerm-1; i>=0; i--){ - exprAnalyze(pTabList, pMaskSet, pWC, i); - } -} - -#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION -/* -** Check to see if the given expression is a LIKE or GLOB operator that -** can be optimized using inequality constraints. Return TRUE if it is -** so and false if not. -** -** In order for the operator to be optimizible, the RHS must be a string -** literal that does not begin with a wildcard. -*/ -static int isLikeOrGlob( - sqlite3 *db, /* The database */ - Expr *pExpr, /* Test this expression */ - int *pnPattern, /* Number of non-wildcard prefix characters */ - int *pisComplete /* True if the only wildcard is % in the last character */ -){ - const char *z; - Expr *pRight, *pLeft; - ExprList *pList; - int c, cnt; - int noCase; - char wc[3]; - CollSeq *pColl; - - if( !sqlite3IsLikeFunction(db, pExpr, &noCase, wc) ){ - return 0; - } - pList = pExpr->pList; - pRight = pList->a[0].pExpr; - if( pRight->op!=TK_STRING ){ - return 0; - } - pLeft = pList->a[1].pExpr; - if( pLeft->op!=TK_COLUMN ){ - return 0; - } - pColl = pLeft->pColl; - if( pColl==0 ){ - pColl = db->pDfltColl; - } - if( (pColl->type!=SQLITE_COLL_BINARY || noCase) && - (pColl->type!=SQLITE_COLL_NOCASE || !noCase) ){ - return 0; - } - sqlite3DequoteExpr(pRight); - z = pRight->token.z; - for(cnt=0; (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2]; cnt++){} - if( cnt==0 || 255==(u8)z[cnt] ){ - return 0; - } - *pisComplete = z[cnt]==wc[0] && z[cnt+1]==0; - *pnPattern = cnt; - return 1; -} -#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ - -/* -** The input to this routine is an WhereTerm structure with only the -** "pExpr" field filled in. The job of this routine is to analyze the -** subexpression and populate all the other fields of the WhereTerm -** structure. -** -** If the expression is of the form "<expr> <op> X" it gets commuted -** to the standard form of "X <op> <expr>". If the expression is of -** the form "X <op> Y" where both X and Y are columns, then the original -** expression is unchanged and a new virtual expression of the form -** "Y <op> X" is added to the WHERE clause and analyzed separately. -*/ -static void exprAnalyze( - SrcList *pSrc, /* the FROM clause */ - ExprMaskSet *pMaskSet, /* table masks */ - WhereClause *pWC, /* the WHERE clause */ - int idxTerm /* Index of the term to be analyzed */ -){ - WhereTerm *pTerm = &pWC->a[idxTerm]; - Expr *pExpr = pTerm->pExpr; - Bitmask prereqLeft; - Bitmask prereqAll; - int nPattern; - int isComplete; - - if( sqlite3_malloc_failed ) return; - prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft); - if( pExpr->op==TK_IN ){ - assert( pExpr->pRight==0 ); - pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->pList) - | exprSelectTableUsage(pMaskSet, pExpr->pSelect); - }else{ - pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight); - } - prereqAll = exprTableUsage(pMaskSet, pExpr); - if( ExprHasProperty(pExpr, EP_FromJoin) ){ - prereqAll |= getMask(pMaskSet, pExpr->iRightJoinTable); - } - pTerm->prereqAll = prereqAll; - pTerm->leftCursor = -1; - pTerm->iParent = -1; - pTerm->operator = 0; - if( allowedOp(pExpr->op) && (pTerm->prereqRight & prereqLeft)==0 ){ - Expr *pLeft = pExpr->pLeft; - Expr *pRight = pExpr->pRight; - if( pLeft->op==TK_COLUMN ){ - pTerm->leftCursor = pLeft->iTable; - pTerm->leftColumn = pLeft->iColumn; - pTerm->operator = operatorMask(pExpr->op); - } - if( pRight && pRight->op==TK_COLUMN ){ - WhereTerm *pNew; - Expr *pDup; - if( pTerm->leftCursor>=0 ){ - int idxNew; - pDup = sqlite3ExprDup(pExpr); - idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC); - if( idxNew==0 ) return; - pNew = &pWC->a[idxNew]; - pNew->iParent = idxTerm; - pTerm = &pWC->a[idxTerm]; - pTerm->nChild = 1; - pTerm->flags |= TERM_COPIED; - }else{ - pDup = pExpr; - pNew = pTerm; - } - exprCommute(pDup); - pLeft = pDup->pLeft; - pNew->leftCursor = pLeft->iTable; - pNew->leftColumn = pLeft->iColumn; - pNew->prereqRight = prereqLeft; - pNew->prereqAll = prereqAll; - pNew->operator = operatorMask(pDup->op); - } - } - -#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION - /* If a term is the BETWEEN operator, create two new virtual terms - ** that define the range that the BETWEEN implements. - */ - else if( pExpr->op==TK_BETWEEN ){ - ExprList *pList = pExpr->pList; - int i; - static const u8 ops[] = {TK_GE, TK_LE}; - assert( pList!=0 ); - assert( pList->nExpr==2 ); - for(i=0; i<2; i++){ - Expr *pNewExpr; - int idxNew; - pNewExpr = sqlite3Expr(ops[i], sqlite3ExprDup(pExpr->pLeft), - sqlite3ExprDup(pList->a[i].pExpr), 0); - idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC); - exprAnalyze(pSrc, pMaskSet, pWC, idxNew); - pTerm = &pWC->a[idxTerm]; - pWC->a[idxNew].iParent = idxTerm; - } - pTerm->nChild = 2; - } -#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */ - -#ifndef SQLITE_OMIT_OR_OPTIMIZATION - /* Attempt to convert OR-connected terms into an IN operator so that - ** they can make use of indices. Example: - ** - ** x = expr1 OR expr2 = x OR x = expr3 - ** - ** is converted into - ** - ** x IN (expr1,expr2,expr3) - */ - else if( pExpr->op==TK_OR ){ - int ok; - int i, j; - int iColumn, iCursor; - WhereClause sOr; - WhereTerm *pOrTerm; - - assert( (pTerm->flags & TERM_DYNAMIC)==0 ); - whereClauseInit(&sOr, pWC->pParse); - whereSplit(&sOr, pExpr, TK_OR); - exprAnalyzeAll(pSrc, pMaskSet, &sOr); - assert( sOr.nTerm>0 ); - j = 0; - do{ - iColumn = sOr.a[j].leftColumn; - iCursor = sOr.a[j].leftCursor; - ok = iCursor>=0; - for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){ - if( pOrTerm->operator!=WO_EQ ){ - goto or_not_possible; - } - if( pOrTerm->leftCursor==iCursor && pOrTerm->leftColumn==iColumn ){ - pOrTerm->flags |= TERM_OR_OK; - }else if( (pOrTerm->flags & TERM_COPIED)!=0 || - ((pOrTerm->flags & TERM_VIRTUAL)!=0 && - (sOr.a[pOrTerm->iParent].flags & TERM_OR_OK)!=0) ){ - pOrTerm->flags &= ~TERM_OR_OK; - }else{ - ok = 0; - } - } - }while( !ok && (sOr.a[j++].flags & TERM_COPIED)!=0 && j<sOr.nTerm ); - if( ok ){ - ExprList *pList = 0; - Expr *pNew, *pDup; - for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){ - if( (pOrTerm->flags & TERM_OR_OK)==0 ) continue; - pDup = sqlite3ExprDup(pOrTerm->pExpr->pRight); - pList = sqlite3ExprListAppend(pList, pDup, 0); - } - pDup = sqlite3Expr(TK_COLUMN, 0, 0, 0); - if( pDup ){ - pDup->iTable = iCursor; - pDup->iColumn = iColumn; - } - pNew = sqlite3Expr(TK_IN, pDup, 0, 0); - if( pNew ){ - pNew->pList = pList; - }else{ - sqlite3ExprListDelete(pList); - } - pTerm->pExpr = pNew; - pTerm->flags |= TERM_DYNAMIC; - exprAnalyze(pSrc, pMaskSet, pWC, idxTerm); - pTerm = &pWC->a[idxTerm]; - } -or_not_possible: - whereClauseClear(&sOr); - } -#endif /* SQLITE_OMIT_OR_OPTIMIZATION */ - -#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION - /* Add constraints to reduce the search space on a LIKE or GLOB - ** operator. - */ - if( isLikeOrGlob(pWC->pParse->db, pExpr, &nPattern, &isComplete) ){ - Expr *pLeft, *pRight; - Expr *pStr1, *pStr2; - Expr *pNewExpr1, *pNewExpr2; - int idxNew1, idxNew2; - - pLeft = pExpr->pList->a[1].pExpr; - pRight = pExpr->pList->a[0].pExpr; - pStr1 = sqlite3Expr(TK_STRING, 0, 0, 0); - if( pStr1 ){ - sqlite3TokenCopy(&pStr1->token, &pRight->token); - pStr1->token.n = nPattern; - } - pStr2 = sqlite3ExprDup(pStr1); - if( pStr2 ){ - assert( pStr2->token.dyn ); - ++*(u8*)&pStr2->token.z[nPattern-1]; - } - pNewExpr1 = sqlite3Expr(TK_GE, sqlite3ExprDup(pLeft), pStr1, 0); - idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC); - exprAnalyze(pSrc, pMaskSet, pWC, idxNew1); - pNewExpr2 = sqlite3Expr(TK_LT, sqlite3ExprDup(pLeft), pStr2, 0); - idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC); - exprAnalyze(pSrc, pMaskSet, pWC, idxNew2); - pTerm = &pWC->a[idxTerm]; - if( isComplete ){ - pWC->a[idxNew1].iParent = idxTerm; - pWC->a[idxNew2].iParent = idxTerm; - pTerm->nChild = 2; - } - } -#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ -} - - -/* -** This routine decides if pIdx can be used to satisfy the ORDER BY -** clause. If it can, it returns 1. If pIdx cannot satisfy the -** ORDER BY clause, this routine returns 0. -** -** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the -** left-most table in the FROM clause of that same SELECT statement and -** the table has a cursor number of "base". pIdx is an index on pTab. -** -** nEqCol is the number of columns of pIdx that are used as equality -** constraints. Any of these columns may be missing from the ORDER BY -** clause and the match can still be a success. -** -** All terms of the ORDER BY that match against the index must be either -** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE -** index do not need to satisfy this constraint.) The *pbRev value is -** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if -** the ORDER BY clause is all ASC. -*/ -static int isSortingIndex( - Parse *pParse, /* Parsing context */ - Index *pIdx, /* The index we are testing */ - Table *pTab, /* The table to be sorted */ - int base, /* Cursor number for pTab */ - ExprList *pOrderBy, /* The ORDER BY clause */ - int nEqCol, /* Number of index columns with == constraints */ - int *pbRev /* Set to 1 if ORDER BY is DESC */ -){ - int i, j; /* Loop counters */ - int sortOrder = SQLITE_SO_ASC; /* Which direction we are sorting */ - int nTerm; /* Number of ORDER BY terms */ - struct ExprList_item *pTerm; /* A term of the ORDER BY clause */ - sqlite3 *db = pParse->db; - - assert( pOrderBy!=0 ); - nTerm = pOrderBy->nExpr; - assert( nTerm>0 ); - - /* Match terms of the ORDER BY clause against columns of - ** the index. - */ - for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<pIdx->nColumn; i++){ - Expr *pExpr; /* The expression of the ORDER BY pTerm */ - CollSeq *pColl; /* The collating sequence of pExpr */ - - pExpr = pTerm->pExpr; - if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){ - /* Can not use an index sort on anything that is not a column in the - ** left-most table of the FROM clause */ - return 0; - } - pColl = sqlite3ExprCollSeq(pParse, pExpr); - if( !pColl ) pColl = db->pDfltColl; - if( pExpr->iColumn!=pIdx->aiColumn[i] || pColl!=pIdx->keyInfo.aColl[i] ){ - /* Term j of the ORDER BY clause does not match column i of the index */ - if( i<nEqCol ){ - /* If an index column that is constrained by == fails to match an - ** ORDER BY term, that is OK. Just ignore that column of the index - */ - continue; - }else{ - /* If an index column fails to match and is not constrained by == - ** then the index cannot satisfy the ORDER BY constraint. - */ - return 0; - } - } - if( i>nEqCol ){ - if( pTerm->sortOrder!=sortOrder ){ - /* Indices can only be used if all ORDER BY terms past the - ** equality constraints are all either DESC or ASC. */ - return 0; - } - }else{ - sortOrder = pTerm->sortOrder; - } - j++; - pTerm++; - } - - /* The index can be used for sorting if all terms of the ORDER BY clause - ** are covered. - */ - if( j>=nTerm ){ - *pbRev = sortOrder==SQLITE_SO_DESC; - return 1; - } - return 0; -} - -/* -** Check table to see if the ORDER BY clause in pOrderBy can be satisfied -** by sorting in order of ROWID. Return true if so and set *pbRev to be -** true for reverse ROWID and false for forward ROWID order. -*/ -static int sortableByRowid( - int base, /* Cursor number for table to be sorted */ - ExprList *pOrderBy, /* The ORDER BY clause */ - int *pbRev /* Set to 1 if ORDER BY is DESC */ -){ - Expr *p; - - assert( pOrderBy!=0 ); - assert( pOrderBy->nExpr>0 ); - p = pOrderBy->a[0].pExpr; - if( pOrderBy->nExpr==1 && p->op==TK_COLUMN && p->iTable==base - && p->iColumn==-1 ){ - *pbRev = pOrderBy->a[0].sortOrder; - return 1; - } - return 0; -} - -/* -** Prepare a crude estimate of the logarithm of the input value. -** The results need not be exact. This is only used for estimating -** the total cost of performing operatings with O(logN) or O(NlogN) -** complexity. Because N is just a guess, it is no great tragedy if -** logN is a little off. -*/ -static double estLog(double N){ - double logN = 1.0; - double x = 10.0; - while( N>x ){ - logN += 1.0; - x *= 10; - } - return logN; -} - -/* -** Find the best index for accessing a particular table. Return a pointer -** to the index, flags that describe how the index should be used, the -** number of equality constraints, and the "cost" for this index. -** -** The lowest cost index wins. The cost is an estimate of the amount of -** CPU and disk I/O need to process the request using the selected index. -** Factors that influence cost include: -** -** * The estimated number of rows that will be retrieved. (The -** fewer the better.) -** -** * Whether or not sorting must occur. -** -** * Whether or not there must be separate lookups in the -** index and in the main table. -** -*/ -static double bestIndex( - Parse *pParse, /* The parsing context */ - WhereClause *pWC, /* The WHERE clause */ - struct SrcList_item *pSrc, /* The FROM clause term to search */ - Bitmask notReady, /* Mask of cursors that are not available */ - ExprList *pOrderBy, /* The order by clause */ - Index **ppIndex, /* Make *ppIndex point to the best index */ - int *pFlags, /* Put flags describing this choice in *pFlags */ - int *pnEq /* Put the number of == or IN constraints here */ -){ - WhereTerm *pTerm; - Index *bestIdx = 0; /* Index that gives the lowest cost */ - double lowestCost = 1.0e99; /* The cost of using bestIdx */ - int bestFlags = 0; /* Flags associated with bestIdx */ - int bestNEq = 0; /* Best value for nEq */ - int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */ - Index *pProbe; /* An index we are evaluating */ - int rev; /* True to scan in reverse order */ - int flags; /* Flags associated with pProbe */ - int nEq; /* Number of == or IN constraints */ - double cost; /* Cost of using pProbe */ - - TRACE(("bestIndex: tbl=%s notReady=%x\n", pSrc->pTab->zName, notReady)); - - /* Check for a rowid=EXPR or rowid IN (...) constraints - */ - pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0); - if( pTerm ){ - Expr *pExpr; - *ppIndex = 0; - bestFlags = WHERE_ROWID_EQ; - if( pTerm->operator & WO_EQ ){ - /* Rowid== is always the best pick. Look no further. Because only - ** a single row is generated, output is always in sorted order */ - *pFlags = WHERE_ROWID_EQ | WHERE_UNIQUE; - *pnEq = 1; - TRACE(("... best is rowid\n")); - return 0.0; - }else if( (pExpr = pTerm->pExpr)->pList!=0 ){ - /* Rowid IN (LIST): cost is NlogN where N is the number of list - ** elements. */ - lowestCost = pExpr->pList->nExpr; - lowestCost *= estLog(lowestCost); - }else{ - /* Rowid IN (SELECT): cost is NlogN where N is the number of rows - ** in the result of the inner select. We have no way to estimate - ** that value so make a wild guess. */ - lowestCost = 200.0; - } - TRACE(("... rowid IN cost: %.9g\n", lowestCost)); - } - - /* Estimate the cost of a table scan. If we do not know how many - ** entries are in the table, use 1 million as a guess. - */ - pProbe = pSrc->pTab->pIndex; - cost = pProbe ? pProbe->aiRowEst[0] : 1000000.0; - TRACE(("... table scan base cost: %.9g\n", cost)); - flags = WHERE_ROWID_RANGE; - - /* Check for constraints on a range of rowids in a table scan. - */ - pTerm = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE|WO_GT|WO_GE, 0); - if( pTerm ){ - if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){ - flags |= WHERE_TOP_LIMIT; - cost *= 0.333; /* Guess that rowid<EXPR eliminates two-thirds or rows */ - } - if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){ - flags |= WHERE_BTM_LIMIT; - cost *= 0.333; /* Guess that rowid>EXPR eliminates two-thirds of rows */ - } - TRACE(("... rowid range reduces cost to %.9g\n", cost)); - }else{ - flags = 0; - } - - /* If the table scan does not satisfy the ORDER BY clause, increase - ** the cost by NlogN to cover the expense of sorting. */ - if( pOrderBy ){ - if( sortableByRowid(iCur, pOrderBy, &rev) ){ - flags |= WHERE_ORDERBY|WHERE_ROWID_RANGE; - if( rev ){ - flags |= WHERE_REVERSE; - } - }else{ - cost += cost*estLog(cost); - TRACE(("... sorting increases cost to %.9g\n", cost)); - } - } - if( cost<lowestCost ){ - lowestCost = cost; - bestFlags = flags; - } - - /* Look at each index. - */ - for(; pProbe; pProbe=pProbe->pNext){ - int i; /* Loop counter */ - double inMultiplier = 1.0; - - TRACE(("... index %s:\n", pProbe->zName)); - - /* Count the number of columns in the index that are satisfied - ** by x=EXPR constraints or x IN (...) constraints. - */ - flags = 0; - for(i=0; i<pProbe->nColumn; i++){ - int j = pProbe->aiColumn[i]; - pTerm = findTerm(pWC, iCur, j, notReady, WO_EQ|WO_IN, pProbe); - if( pTerm==0 ) break; - flags |= WHERE_COLUMN_EQ; - if( pTerm->operator & WO_IN ){ - Expr *pExpr = pTerm->pExpr; - flags |= WHERE_COLUMN_IN; - if( pExpr->pSelect!=0 ){ - inMultiplier *= 100.0; - }else if( pExpr->pList!=0 ){ - inMultiplier *= pExpr->pList->nExpr + 1.0; - } - } - } - cost = pProbe->aiRowEst[i] * inMultiplier * estLog(inMultiplier); - nEq = i; - if( pProbe->onError!=OE_None && (flags & WHERE_COLUMN_IN)==0 - && nEq==pProbe->nColumn ){ - flags |= WHERE_UNIQUE; - } - TRACE(("...... nEq=%d inMult=%.9g cost=%.9g\n", nEq, inMultiplier, cost)); - - /* Look for range constraints - */ - if( nEq<pProbe->nColumn ){ - int j = pProbe->aiColumn[nEq]; - pTerm = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pProbe); - if( pTerm ){ - flags |= WHERE_COLUMN_RANGE; - if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){ - flags |= WHERE_TOP_LIMIT; - cost *= 0.333; - } - if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){ - flags |= WHERE_BTM_LIMIT; - cost *= 0.333; - } - TRACE(("...... range reduces cost to %.9g\n", cost)); - } - } - - /* Add the additional cost of sorting if that is a factor. - */ - if( pOrderBy ){ - if( (flags & WHERE_COLUMN_IN)==0 && - isSortingIndex(pParse,pProbe,pSrc->pTab,iCur,pOrderBy,nEq,&rev) ){ - if( flags==0 ){ - flags = WHERE_COLUMN_RANGE; - } - flags |= WHERE_ORDERBY; - if( rev ){ - flags |= WHERE_REVERSE; - } - }else{ - cost += cost*estLog(cost); - TRACE(("...... orderby increases cost to %.9g\n", cost)); - } - } - - /* Check to see if we can get away with using just the index without - ** ever reading the table. If that is the case, then halve the - ** cost of this index. - */ - if( flags && pSrc->colUsed < (((Bitmask)1)<<(BMS-1)) ){ - Bitmask m = pSrc->colUsed; - int j; - for(j=0; j<pProbe->nColumn; j++){ - int x = pProbe->aiColumn[j]; - if( x<BMS-1 ){ - m &= ~(((Bitmask)1)<<x); - } - } - if( m==0 ){ - flags |= WHERE_IDX_ONLY; - cost *= 0.5; - TRACE(("...... idx-only reduces cost to %.9g\n", cost)); - } - } - - /* If this index has achieved the lowest cost so far, then use it. - */ - if( cost < lowestCost ){ - bestIdx = pProbe; - lowestCost = cost; - assert( flags!=0 ); - bestFlags = flags; - bestNEq = nEq; - } - } - - /* Report the best result - */ - *ppIndex = bestIdx; - TRACE(("best index is %s, cost=%.9g, flags=%x, nEq=%d\n", - bestIdx ? bestIdx->zName : "(none)", lowestCost, bestFlags, bestNEq)); - *pFlags = bestFlags; - *pnEq = bestNEq; - return lowestCost; -} - - -/* -** Disable a term in the WHERE clause. Except, do not disable the term -** if it controls a LEFT OUTER JOIN and it did not originate in the ON -** or USING clause of that join. -** -** Consider the term t2.z='ok' in the following queries: -** -** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok' -** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok' -** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok' -** -** The t2.z='ok' is disabled in the in (2) because it originates -** in the ON clause. The term is disabled in (3) because it is not part -** of a LEFT OUTER JOIN. In (1), the term is not disabled. -** -** Disabling a term causes that term to not be tested in the inner loop -** of the join. Disabling is an optimization. When terms are satisfied -** by indices, we disable them to prevent redundant tests in the inner -** loop. We would get the correct results if nothing were ever disabled, -** but joins might run a little slower. The trick is to disable as much -** as we can without disabling too much. If we disabled in (1), we'd get -** the wrong answer. See ticket #813. -*/ -static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){ - if( pTerm - && (pTerm->flags & TERM_CODED)==0 - && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin)) - ){ - pTerm->flags |= TERM_CODED; - if( pTerm->iParent>=0 ){ - WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent]; - if( (--pOther->nChild)==0 ){ - disableTerm(pLevel, pOther); - } - } - } -} - -/* -** Generate code that builds a probe for an index. Details: -** -** * Check the top nColumn entries on the stack. If any -** of those entries are NULL, jump immediately to brk, -** which is the loop exit, since no index entry will match -** if any part of the key is NULL. -** -** * Construct a probe entry from the top nColumn entries in -** the stack with affinities appropriate for index pIdx. -*/ -static void buildIndexProbe(Vdbe *v, int nColumn, int brk, Index *pIdx){ - sqlite3VdbeAddOp(v, OP_NotNull, -nColumn, sqlite3VdbeCurrentAddr(v)+3); - sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0); - sqlite3VdbeAddOp(v, OP_Goto, 0, brk); - sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0); - sqlite3IndexAffinityStr(v, pIdx); -} - - -/* -** Generate code for a single equality term of the WHERE clause. An equality -** term can be either X=expr or X IN (...). pTerm is the term to be -** coded. -** -** The current value for the constraint is left on the top of the stack. -** -** For a constraint of the form X=expr, the expression is evaluated and its -** result is left on the stack. For constraints of the form X IN (...) -** this routine sets up a loop that will iterate over all values of X. -*/ -static void codeEqualityTerm( - Parse *pParse, /* The parsing context */ - WhereTerm *pTerm, /* The term of the WHERE clause to be coded */ - int brk, /* Jump here to abandon the loop */ - WhereLevel *pLevel /* When level of the FROM clause we are working on */ -){ - Expr *pX = pTerm->pExpr; - if( pX->op!=TK_IN ){ - assert( pX->op==TK_EQ ); - sqlite3ExprCode(pParse, pX->pRight); -#ifndef SQLITE_OMIT_SUBQUERY - }else{ - int iTab; - int *aIn; - Vdbe *v = pParse->pVdbe; - - sqlite3CodeSubselect(pParse, pX); - iTab = pX->iTable; - sqlite3VdbeAddOp(v, OP_Rewind, iTab, brk); - VdbeComment((v, "# %.*s", pX->span.n, pX->span.z)); - pLevel->nIn++; - sqlite3ReallocOrFree((void**)&pLevel->aInLoop, - sizeof(pLevel->aInLoop[0])*3*pLevel->nIn); - aIn = pLevel->aInLoop; - if( aIn ){ - aIn += pLevel->nIn*3 - 3; - aIn[0] = OP_Next; - aIn[1] = iTab; - aIn[2] = sqlite3VdbeAddOp(v, OP_Column, iTab, 0); - }else{ - pLevel->nIn = 0; - } -#endif - } - disableTerm(pLevel, pTerm); -} - -/* -** Generate code that will evaluate all == and IN constraints for an -** index. The values for all constraints are left on the stack. -** -** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c). -** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10 -** The index has as many as three equality constraints, but in this -** example, the third "c" value is an inequality. So only two -** constraints are coded. This routine will generate code to evaluate -** a==5 and b IN (1,2,3). The current values for a and b will be left -** on the stack - a is the deepest and b the shallowest. -** -** In the example above nEq==2. But this subroutine works for any value -** of nEq including 0. If nEq==0, this routine is nearly a no-op. -** The only thing it does is allocate the pLevel->iMem memory cell. -** -** This routine always allocates at least one memory cell and puts -** the address of that memory cell in pLevel->iMem. The code that -** calls this routine will use pLevel->iMem to store the termination -** key value of the loop. If one or more IN operators appear, then -** this routine allocates an additional nEq memory cells for internal -** use. -*/ -static void codeAllEqualityTerms( - Parse *pParse, /* Parsing context */ - WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */ - WhereClause *pWC, /* The WHERE clause */ - Bitmask notReady, /* Which parts of FROM have not yet been coded */ - int brk /* Jump here to end the loop */ -){ - int nEq = pLevel->nEq; /* The number of == or IN constraints to code */ - int termsInMem = 0; /* If true, store value in mem[] cells */ - Vdbe *v = pParse->pVdbe; /* The virtual machine under construction */ - Index *pIdx = pLevel->pIdx; /* The index being used for this loop */ - int iCur = pLevel->iTabCur; /* The cursor of the table */ - WhereTerm *pTerm; /* A single constraint term */ - int j; /* Loop counter */ - - /* Figure out how many memory cells we will need then allocate them. - ** We always need at least one used to store the loop terminator - ** value. If there are IN operators we'll need one for each == or - ** IN constraint. - */ - pLevel->iMem = pParse->nMem++; - if( pLevel->flags & WHERE_COLUMN_IN ){ - pParse->nMem += pLevel->nEq; - termsInMem = 1; - } - - /* Evaluate the equality constraints - */ - for(j=0; j<pIdx->nColumn; j++){ - int k = pIdx->aiColumn[j]; - pTerm = findTerm(pWC, iCur, k, notReady, WO_EQ|WO_IN, pIdx); - if( pTerm==0 ) break; - assert( (pTerm->flags & TERM_CODED)==0 ); - codeEqualityTerm(pParse, pTerm, brk, pLevel); - if( termsInMem ){ - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem+j+1, 1); - } - } - assert( j==nEq ); - - /* Make sure all the constraint values are on the top of the stack - */ - if( termsInMem ){ - for(j=0; j<nEq; j++){ - sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem+j+1, 0); - } - } -} - -#if defined(SQLITE_TEST) -/* -** The following variable holds a text description of query plan generated -** by the most recent call to sqlite3WhereBegin(). Each call to WhereBegin -** overwrites the previous. This information is used for testing and -** analysis only. -*/ -char sqlite3_query_plan[BMS*2*40]; /* Text of the join */ -static int nQPlan = 0; /* Next free slow in _query_plan[] */ - -#endif /* SQLITE_TEST */ - - - -/* -** Generate the beginning of the loop used for WHERE clause processing. -** The return value is a pointer to an opaque structure that contains -** information needed to terminate the loop. Later, the calling routine -** should invoke sqlite3WhereEnd() with the return value of this function -** in order to complete the WHERE clause processing. -** -** If an error occurs, this routine returns NULL. -** -** The basic idea is to do a nested loop, one loop for each table in -** the FROM clause of a select. (INSERT and UPDATE statements are the -** same as a SELECT with only a single table in the FROM clause.) For -** example, if the SQL is this: -** -** SELECT * FROM t1, t2, t3 WHERE ...; -** -** Then the code generated is conceptually like the following: -** -** foreach row1 in t1 do \ Code generated -** foreach row2 in t2 do |-- by sqlite3WhereBegin() -** foreach row3 in t3 do / -** ... -** end \ Code generated -** end |-- by sqlite3WhereEnd() -** end / -** -** Note that the loops might not be nested in the order in which they -** appear in the FROM clause if a different order is better able to make -** use of indices. Note also that when the IN operator appears in -** the WHERE clause, it might result in additional nested loops for -** scanning through all values on the right-hand side of the IN. -** -** There are Btree cursors associated with each table. t1 uses cursor -** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor. -** And so forth. This routine generates code to open those VDBE cursors -** and sqlite3WhereEnd() generates the code to close them. -** -** The code that sqlite3WhereBegin() generates leaves the cursors named -** in pTabList pointing at their appropriate entries. The [...] code -** can use OP_Column and OP_Rowid opcodes on these cursors to extract -** data from the various tables of the loop. -** -** If the WHERE clause is empty, the foreach loops must each scan their -** entire tables. Thus a three-way join is an O(N^3) operation. But if -** the tables have indices and there are terms in the WHERE clause that -** refer to those indices, a complete table scan can be avoided and the -** code will run much faster. Most of the work of this routine is checking -** to see if there are indices that can be used to speed up the loop. -** -** Terms of the WHERE clause are also used to limit which rows actually -** make it to the "..." in the middle of the loop. After each "foreach", -** terms of the WHERE clause that use only terms in that loop and outer -** loops are evaluated and if false a jump is made around all subsequent -** inner loops (or around the "..." if the test occurs within the inner- -** most loop) -** -** OUTER JOINS -** -** An outer join of tables t1 and t2 is conceptally coded as follows: -** -** foreach row1 in t1 do -** flag = 0 -** foreach row2 in t2 do -** start: -** ... -** flag = 1 -** end -** if flag==0 then -** move the row2 cursor to a null row -** goto start -** fi -** end -** -** ORDER BY CLAUSE PROCESSING -** -** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement, -** if there is one. If there is no ORDER BY clause or if this routine -** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL. -** -** If an index can be used so that the natural output order of the table -** scan is correct for the ORDER BY clause, then that index is used and -** *ppOrderBy is set to NULL. This is an optimization that prevents an -** unnecessary sort of the result set if an index appropriate for the -** ORDER BY clause already exists. -** -** If the where clause loops cannot be arranged to provide the correct -** output order, then the *ppOrderBy is unchanged. -*/ -WhereInfo *sqlite3WhereBegin( - Parse *pParse, /* The parser context */ - SrcList *pTabList, /* A list of all tables to be scanned */ - Expr *pWhere, /* The WHERE clause */ - ExprList **ppOrderBy /* An ORDER BY clause, or NULL */ -){ - int i; /* Loop counter */ - WhereInfo *pWInfo; /* Will become the return value of this function */ - Vdbe *v = pParse->pVdbe; /* The virtual database engine */ - int brk, cont = 0; /* Addresses used during code generation */ - Bitmask notReady; /* Cursors that are not yet positioned */ - WhereTerm *pTerm; /* A single term in the WHERE clause */ - ExprMaskSet maskSet; /* The expression mask set */ - WhereClause wc; /* The WHERE clause is divided into these terms */ - struct SrcList_item *pTabItem; /* A single entry from pTabList */ - WhereLevel *pLevel; /* A single level in the pWInfo list */ - int iFrom; /* First unused FROM clause element */ - int andFlags; /* AND-ed combination of all wc.a[].flags */ - - /* The number of tables in the FROM clause is limited by the number of - ** bits in a Bitmask - */ - if( pTabList->nSrc>BMS ){ - sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS); - return 0; - } - - /* Split the WHERE clause into separate subexpressions where each - ** subexpression is separated by an AND operator. - */ - initMaskSet(&maskSet); - whereClauseInit(&wc, pParse); - whereSplit(&wc, pWhere, TK_AND); - - /* Allocate and initialize the WhereInfo structure that will become the - ** return value. - */ - pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel)); - if( sqlite3_malloc_failed ){ - goto whereBeginNoMem; - } - pWInfo->pParse = pParse; - pWInfo->pTabList = pTabList; - pWInfo->iBreak = sqlite3VdbeMakeLabel(v); - - /* Special case: a WHERE clause that is constant. Evaluate the - ** expression and either jump over all of the code or fall thru. - */ - if( pWhere && (pTabList->nSrc==0 || sqlite3ExprIsConstant(pWhere)) ){ - sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1); - pWhere = 0; - } - - /* Analyze all of the subexpressions. Note that exprAnalyze() might - ** add new virtual terms onto the end of the WHERE clause. We do not - ** want to analyze these virtual terms, so start analyzing at the end - ** and work forward so that the added virtual terms are never processed. - */ - for(i=0; i<pTabList->nSrc; i++){ - createMask(&maskSet, pTabList->a[i].iCursor); - } - exprAnalyzeAll(pTabList, &maskSet, &wc); - if( sqlite3_malloc_failed ){ - goto whereBeginNoMem; - } - - /* Chose the best index to use for each table in the FROM clause. - ** - ** This loop fills in the following fields: - ** - ** pWInfo->a[].pIdx The index to use for this level of the loop. - ** pWInfo->a[].flags WHERE_xxx flags associated with pIdx - ** pWInfo->a[].nEq The number of == and IN constraints - ** pWInfo->a[].iFrom When term of the FROM clause is being coded - ** pWInfo->a[].iTabCur The VDBE cursor for the database table - ** pWInfo->a[].iIdxCur The VDBE cursor for the index - ** - ** This loop also figures out the nesting order of tables in the FROM - ** clause. - */ - notReady = ~(Bitmask)0; - pTabItem = pTabList->a; - pLevel = pWInfo->a; - andFlags = ~0; - TRACE(("*** Optimizer Start ***\n")); - for(i=iFrom=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ - Index *pIdx; /* Index for FROM table at pTabItem */ - int flags; /* Flags asssociated with pIdx */ - int nEq; /* Number of == or IN constraints */ - double cost; /* The cost for pIdx */ - int j; /* For looping over FROM tables */ - Index *pBest = 0; /* The best index seen so far */ - int bestFlags = 0; /* Flags associated with pBest */ - int bestNEq = 0; /* nEq associated with pBest */ - double lowestCost = 1.0e99; /* Cost of the pBest */ - int bestJ; /* The value of j */ - Bitmask m; /* Bitmask value for j or bestJ */ - - for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){ - m = getMask(&maskSet, pTabItem->iCursor); - if( (m & notReady)==0 ){ - if( j==iFrom ) iFrom++; - continue; - } - cost = bestIndex(pParse, &wc, pTabItem, notReady, - (i==0 && ppOrderBy) ? *ppOrderBy : 0, - &pIdx, &flags, &nEq); - if( cost<lowestCost ){ - lowestCost = cost; - pBest = pIdx; - bestFlags = flags; - bestNEq = nEq; - bestJ = j; - } - if( (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0 - || (j>0 && (pTabItem[-1].jointype & (JT_LEFT|JT_CROSS))!=0) - ){ - break; - } - } - TRACE(("*** Optimizer choose table %d for loop %d\n", bestJ, - pLevel-pWInfo->a)); - if( (bestFlags & WHERE_ORDERBY)!=0 ){ - *ppOrderBy = 0; - } - andFlags &= bestFlags; - pLevel->flags = bestFlags; - pLevel->pIdx = pBest; - pLevel->nEq = bestNEq; - pLevel->aInLoop = 0; - pLevel->nIn = 0; - if( pBest ){ - pLevel->iIdxCur = pParse->nTab++; - }else{ - pLevel->iIdxCur = -1; - } - notReady &= ~getMask(&maskSet, pTabList->a[bestJ].iCursor); - pLevel->iFrom = bestJ; - } - TRACE(("*** Optimizer Finished ***\n")); - - /* If the total query only selects a single row, then the ORDER BY - ** clause is irrelevant. - */ - if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){ - *ppOrderBy = 0; - } - - /* Open all tables in the pTabList and any indices selected for - ** searching those tables. - */ - sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */ - pLevel = pWInfo->a; - for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ - Table *pTab; - Index *pIx; - int iIdxCur = pLevel->iIdxCur; - -#ifndef SQLITE_OMIT_EXPLAIN - if( pParse->explain==2 ){ - char *zMsg; - struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom]; - zMsg = sqlite3MPrintf("TABLE %s", pItem->zName); - if( pItem->zAlias ){ - zMsg = sqlite3MPrintf("%z AS %s", zMsg, pItem->zAlias); - } - if( (pIx = pLevel->pIdx)!=0 ){ - zMsg = sqlite3MPrintf("%z WITH INDEX %s", zMsg, pIx->zName); - } - sqlite3VdbeOp3(v, OP_Explain, i, pLevel->iFrom, zMsg, P3_DYNAMIC); - } -#endif /* SQLITE_OMIT_EXPLAIN */ - pTabItem = &pTabList->a[pLevel->iFrom]; - pTab = pTabItem->pTab; - if( pTab->isTransient || pTab->pSelect ) continue; - if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){ - sqlite3OpenTableForReading(v, pTabItem->iCursor, pTab); - } - pLevel->iTabCur = pTabItem->iCursor; - if( (pIx = pLevel->pIdx)!=0 ){ - sqlite3VdbeAddOp(v, OP_Integer, pIx->iDb, 0); - VdbeComment((v, "# %s", pIx->zName)); - sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum, - (char*)&pIx->keyInfo, P3_KEYINFO); - } - if( (pLevel->flags & WHERE_IDX_ONLY)!=0 ){ - sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1); - } - sqlite3CodeVerifySchema(pParse, pTab->iDb); - } - pWInfo->iTop = sqlite3VdbeCurrentAddr(v); - - /* Generate the code to do the search. Each iteration of the for - ** loop below generates code for a single nested loop of the VM - ** program. - */ - notReady = ~(Bitmask)0; - for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ - int j; - int iCur = pTabItem->iCursor; /* The VDBE cursor for the table */ - Index *pIdx; /* The index we will be using */ - int iIdxCur; /* The VDBE cursor for the index */ - int omitTable; /* True if we use the index only */ - int bRev; /* True if we need to scan in reverse order */ - - pTabItem = &pTabList->a[pLevel->iFrom]; - iCur = pTabItem->iCursor; - pIdx = pLevel->pIdx; - iIdxCur = pLevel->iIdxCur; - bRev = (pLevel->flags & WHERE_REVERSE)!=0; - omitTable = (pLevel->flags & WHERE_IDX_ONLY)!=0; - - /* Create labels for the "break" and "continue" instructions - ** for the current loop. Jump to brk to break out of a loop. - ** Jump to cont to go immediately to the next iteration of the - ** loop. - */ - brk = pLevel->brk = sqlite3VdbeMakeLabel(v); - cont = pLevel->cont = sqlite3VdbeMakeLabel(v); - - /* If this is the right table of a LEFT OUTER JOIN, allocate and - ** initialize a memory cell that records if this table matches any - ** row of the left table of the join. - */ - if( pLevel->iFrom>0 && (pTabItem[-1].jointype & JT_LEFT)!=0 ){ - if( !pParse->nMem ) pParse->nMem++; - pLevel->iLeftJoin = pParse->nMem++; - sqlite3VdbeAddOp(v, OP_MemInt, 0, pLevel->iLeftJoin); - VdbeComment((v, "# init LEFT JOIN no-match flag")); - } - - if( pLevel->flags & WHERE_ROWID_EQ ){ - /* Case 1: We can directly reference a single row using an - ** equality comparison against the ROWID field. Or - ** we reference multiple rows using a "rowid IN (...)" - ** construct. - */ - pTerm = findTerm(&wc, iCur, -1, notReady, WO_EQ|WO_IN, 0); - assert( pTerm!=0 ); - assert( pTerm->pExpr!=0 ); - assert( pTerm->leftCursor==iCur ); - assert( omitTable==0 ); - codeEqualityTerm(pParse, pTerm, brk, pLevel); - sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk); - sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk); - VdbeComment((v, "pk")); - pLevel->op = OP_Noop; - }else if( pLevel->flags & WHERE_ROWID_RANGE ){ - /* Case 2: We have an inequality comparison against the ROWID field. - */ - int testOp = OP_Noop; - int start; - WhereTerm *pStart, *pEnd; - - assert( omitTable==0 ); - pStart = findTerm(&wc, iCur, -1, notReady, WO_GT|WO_GE, 0); - pEnd = findTerm(&wc, iCur, -1, notReady, WO_LT|WO_LE, 0); - if( bRev ){ - pTerm = pStart; - pStart = pEnd; - pEnd = pTerm; - } - if( pStart ){ - Expr *pX; - pX = pStart->pExpr; - assert( pX!=0 ); - assert( pStart->leftCursor==iCur ); - sqlite3ExprCode(pParse, pX->pRight); - sqlite3VdbeAddOp(v, OP_ForceInt, pX->op==TK_LE || pX->op==TK_GT, brk); - sqlite3VdbeAddOp(v, bRev ? OP_MoveLt : OP_MoveGe, iCur, brk); - VdbeComment((v, "pk")); - disableTerm(pLevel, pStart); - }else{ - sqlite3VdbeAddOp(v, bRev ? OP_Last : OP_Rewind, iCur, brk); - } - if( pEnd ){ - Expr *pX; - pX = pEnd->pExpr; - assert( pX!=0 ); - assert( pEnd->leftCursor==iCur ); - sqlite3ExprCode(pParse, pX->pRight); - pLevel->iMem = pParse->nMem++; - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); - if( pX->op==TK_LT || pX->op==TK_GT ){ - testOp = bRev ? OP_Le : OP_Ge; - }else{ - testOp = bRev ? OP_Lt : OP_Gt; - } - disableTerm(pLevel, pEnd); - } - start = sqlite3VdbeCurrentAddr(v); - pLevel->op = bRev ? OP_Prev : OP_Next; - pLevel->p1 = iCur; - pLevel->p2 = start; - if( testOp!=OP_Noop ){ - sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0); - sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); - sqlite3VdbeAddOp(v, testOp, 'n', brk); - } - }else if( pLevel->flags & WHERE_COLUMN_RANGE ){ - /* Case 3: The WHERE clause term that refers to the right-most - ** column of the index is an inequality. For example, if - ** the index is on (x,y,z) and the WHERE clause is of the - ** form "x=5 AND y<10" then this case is used. Only the - ** right-most column can be an inequality - the rest must - ** use the "==" and "IN" operators. - ** - ** This case is also used when there are no WHERE clause - ** constraints but an index is selected anyway, in order - ** to force the output order to conform to an ORDER BY. - */ - int start; - int nEq = pLevel->nEq; - int leFlag=0, geFlag=0; - int testOp; - int topLimit = (pLevel->flags & WHERE_TOP_LIMIT)!=0; - int btmLimit = (pLevel->flags & WHERE_BTM_LIMIT)!=0; - - /* Generate code to evaluate all constraint terms using == or IN - ** and level the values of those terms on the stack. - */ - codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk); - - /* Duplicate the equality term values because they will all be - ** used twice: once to make the termination key and once to make the - ** start key. - */ - for(j=0; j<nEq; j++){ - sqlite3VdbeAddOp(v, OP_Dup, nEq-1, 0); - } - - /* Generate the termination key. This is the key value that - ** will end the search. There is no termination key if there - ** are no equality terms and no "X<..." term. - ** - ** 2002-Dec-04: On a reverse-order scan, the so-called "termination" - ** key computed here really ends up being the start key. - */ - if( topLimit ){ - Expr *pX; - int k = pIdx->aiColumn[j]; - pTerm = findTerm(&wc, iCur, k, notReady, WO_LT|WO_LE, pIdx); - assert( pTerm!=0 ); - pX = pTerm->pExpr; - assert( (pTerm->flags & TERM_CODED)==0 ); - sqlite3ExprCode(pParse, pX->pRight); - leFlag = pX->op==TK_LE; - disableTerm(pLevel, pTerm); - testOp = OP_IdxGE; - }else{ - testOp = nEq>0 ? OP_IdxGE : OP_Noop; - leFlag = 1; - } - if( testOp!=OP_Noop ){ - int nCol = nEq + topLimit; - pLevel->iMem = pParse->nMem++; - buildIndexProbe(v, nCol, brk, pIdx); - if( bRev ){ - int op = leFlag ? OP_MoveLe : OP_MoveLt; - sqlite3VdbeAddOp(v, op, iIdxCur, brk); - }else{ - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); - } - }else if( bRev ){ - sqlite3VdbeAddOp(v, OP_Last, iIdxCur, brk); - } - - /* Generate the start key. This is the key that defines the lower - ** bound on the search. There is no start key if there are no - ** equality terms and if there is no "X>..." term. In - ** that case, generate a "Rewind" instruction in place of the - ** start key search. - ** - ** 2002-Dec-04: In the case of a reverse-order search, the so-called - ** "start" key really ends up being used as the termination key. - */ - if( btmLimit ){ - Expr *pX; - int k = pIdx->aiColumn[j]; - pTerm = findTerm(&wc, iCur, k, notReady, WO_GT|WO_GE, pIdx); - assert( pTerm!=0 ); - pX = pTerm->pExpr; - assert( (pTerm->flags & TERM_CODED)==0 ); - sqlite3ExprCode(pParse, pX->pRight); - geFlag = pX->op==TK_GE; - disableTerm(pLevel, pTerm); - }else{ - geFlag = 1; - } - if( nEq>0 || btmLimit ){ - int nCol = nEq + btmLimit; - buildIndexProbe(v, nCol, brk, pIdx); - if( bRev ){ - pLevel->iMem = pParse->nMem++; - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); - testOp = OP_IdxLT; - }else{ - int op = geFlag ? OP_MoveGe : OP_MoveGt; - sqlite3VdbeAddOp(v, op, iIdxCur, brk); - } - }else if( bRev ){ - testOp = OP_Noop; - }else{ - sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, brk); - } - - /* Generate the the top of the loop. If there is a termination - ** key we have to test for that key and abort at the top of the - ** loop. - */ - start = sqlite3VdbeCurrentAddr(v); - if( testOp!=OP_Noop ){ - sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); - sqlite3VdbeAddOp(v, testOp, iIdxCur, brk); - if( (leFlag && !bRev) || (!geFlag && bRev) ){ - sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC); - } - } - sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0); - sqlite3VdbeAddOp(v, OP_IdxIsNull, nEq + topLimit, cont); - if( !omitTable ){ - sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0); - sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); - } - - /* Record the instruction used to terminate the loop. - */ - pLevel->op = bRev ? OP_Prev : OP_Next; - pLevel->p1 = iIdxCur; - pLevel->p2 = start; - }else if( pLevel->flags & WHERE_COLUMN_EQ ){ - /* Case 4: There is an index and all terms of the WHERE clause that - ** refer to the index using the "==" or "IN" operators. - */ - int start; - int nEq = pLevel->nEq; - - /* Generate code to evaluate all constraint terms using == or IN - ** and leave the values of those terms on the stack. - */ - codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk); - - /* Generate a single key that will be used to both start and terminate - ** the search - */ - buildIndexProbe(v, nEq, brk, pIdx); - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 0); - - /* Generate code (1) to move to the first matching element of the table. - ** Then generate code (2) that jumps to "brk" after the cursor is past - ** the last matching element of the table. The code (1) is executed - ** once to initialize the search, the code (2) is executed before each - ** iteration of the scan to see if the scan has finished. */ - if( bRev ){ - /* Scan in reverse order */ - sqlite3VdbeAddOp(v, OP_MoveLe, iIdxCur, brk); - start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); - sqlite3VdbeAddOp(v, OP_IdxLT, iIdxCur, brk); - pLevel->op = OP_Prev; - }else{ - /* Scan in the forward order */ - sqlite3VdbeAddOp(v, OP_MoveGe, iIdxCur, brk); - start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); - sqlite3VdbeOp3(v, OP_IdxGE, iIdxCur, brk, "+", P3_STATIC); - pLevel->op = OP_Next; - } - sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0); - sqlite3VdbeAddOp(v, OP_IdxIsNull, nEq, cont); - if( !omitTable ){ - sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0); - sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); - } - pLevel->p1 = iIdxCur; - pLevel->p2 = start; - }else{ - /* Case 5: There is no usable index. We must do a complete - ** scan of the entire table. - */ - assert( omitTable==0 ); - assert( bRev==0 ); - pLevel->op = OP_Next; - pLevel->p1 = iCur; - pLevel->p2 = 1 + sqlite3VdbeAddOp(v, OP_Rewind, iCur, brk); - } - notReady &= ~getMask(&maskSet, iCur); - - /* Insert code to test every subexpression that can be completely - ** computed using the current set of tables. - */ - for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){ - Expr *pE; - if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue; - if( (pTerm->prereqAll & notReady)!=0 ) continue; - pE = pTerm->pExpr; - assert( pE!=0 ); - if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){ - continue; - } - sqlite3ExprIfFalse(pParse, pE, cont, 1); - pTerm->flags |= TERM_CODED; - } - - /* For a LEFT OUTER JOIN, generate code that will record the fact that - ** at least one row of the right table has matched the left table. - */ - if( pLevel->iLeftJoin ){ - pLevel->top = sqlite3VdbeCurrentAddr(v); - sqlite3VdbeAddOp(v, OP_MemInt, 1, pLevel->iLeftJoin); - VdbeComment((v, "# record LEFT JOIN hit")); - for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){ - if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue; - if( (pTerm->prereqAll & notReady)!=0 ) continue; - assert( pTerm->pExpr ); - sqlite3ExprIfFalse(pParse, pTerm->pExpr, cont, 1); - pTerm->flags |= TERM_CODED; - } - } - } - -#ifdef SQLITE_TEST /* For testing and debugging use only */ - /* Record in the query plan information about the current table - ** and the index used to access it (if any). If the table itself - ** is not used, its name is just '{}'. If no index is used - ** the index is listed as "{}". If the primary key is used the - ** index name is '*'. - */ - for(i=0; i<pTabList->nSrc; i++){ - char *z; - int n; - pLevel = &pWInfo->a[i]; - pTabItem = &pTabList->a[pLevel->iFrom]; - z = pTabItem->zAlias; - if( z==0 ) z = pTabItem->pTab->zName; - n = strlen(z); - if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){ - if( pLevel->flags & WHERE_IDX_ONLY ){ - strcpy(&sqlite3_query_plan[nQPlan], "{}"); - nQPlan += 2; - }else{ - strcpy(&sqlite3_query_plan[nQPlan], z); - nQPlan += n; - } - sqlite3_query_plan[nQPlan++] = ' '; - } - if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){ - strcpy(&sqlite3_query_plan[nQPlan], "* "); - nQPlan += 2; - }else if( pLevel->pIdx==0 ){ - strcpy(&sqlite3_query_plan[nQPlan], "{} "); - nQPlan += 3; - }else{ - n = strlen(pLevel->pIdx->zName); - if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){ - strcpy(&sqlite3_query_plan[nQPlan], pLevel->pIdx->zName); - nQPlan += n; - sqlite3_query_plan[nQPlan++] = ' '; - } - } - } - while( nQPlan>0 && sqlite3_query_plan[nQPlan-1]==' ' ){ - sqlite3_query_plan[--nQPlan] = 0; - } - sqlite3_query_plan[nQPlan] = 0; - nQPlan = 0; -#endif /* SQLITE_TEST // Testing and debugging use only */ - - /* Record the continuation address in the WhereInfo structure. Then - ** clean up and return. - */ - pWInfo->iContinue = cont; - whereClauseClear(&wc); - return pWInfo; - - /* Jump here if malloc fails */ -whereBeginNoMem: - whereClauseClear(&wc); - sqliteFree(pWInfo); - return 0; -} - -/* -** Generate the end of the WHERE loop. See comments on -** sqlite3WhereBegin() for additional information. -*/ -void sqlite3WhereEnd(WhereInfo *pWInfo){ - Vdbe *v = pWInfo->pParse->pVdbe; - int i; - WhereLevel *pLevel; - SrcList *pTabList = pWInfo->pTabList; - - /* Generate loop termination code. - */ - for(i=pTabList->nSrc-1; i>=0; i--){ - pLevel = &pWInfo->a[i]; - sqlite3VdbeResolveLabel(v, pLevel->cont); - if( pLevel->op!=OP_Noop ){ - sqlite3VdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2); - } - sqlite3VdbeResolveLabel(v, pLevel->brk); - if( pLevel->nIn ){ - int *a; - int j; - for(j=pLevel->nIn, a=&pLevel->aInLoop[j*3-3]; j>0; j--, a-=3){ - sqlite3VdbeAddOp(v, a[0], a[1], a[2]); - } - sqliteFree(pLevel->aInLoop); - } - if( pLevel->iLeftJoin ){ - int addr; - addr = sqlite3VdbeAddOp(v, OP_IfMemPos, pLevel->iLeftJoin, 0); - sqlite3VdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0); - if( pLevel->iIdxCur>=0 ){ - sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iIdxCur, 0); - } - sqlite3VdbeAddOp(v, OP_Goto, 0, pLevel->top); - sqlite3VdbeJumpHere(v, addr); - } - } - - /* The "break" point is here, just past the end of the outer loop. - ** Set it. - */ - sqlite3VdbeResolveLabel(v, pWInfo->iBreak); - - /* Close all of the cursors that were opened by sqlite3WhereBegin. - */ - for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ - struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom]; - Table *pTab = pTabItem->pTab; - assert( pTab!=0 ); - if( pTab->isTransient || pTab->pSelect ) continue; - if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){ - sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0); - } - if( pLevel->pIdx!=0 ){ - sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0); - } - - /* Make cursor substitutions for cases where we want to use - ** just the index and never reference the table. - ** - ** Calls to the code generator in between sqlite3WhereBegin and - ** sqlite3WhereEnd will have created code that references the table - ** directly. This loop scans all that code looking for opcodes - ** that reference the table and converts them into opcodes that - ** reference the index. - */ - if( pLevel->flags & WHERE_IDX_ONLY ){ - int i, j, last; - VdbeOp *pOp; - Index *pIdx = pLevel->pIdx; - - assert( pIdx!=0 ); - pOp = sqlite3VdbeGetOp(v, pWInfo->iTop); - last = sqlite3VdbeCurrentAddr(v); - for(i=pWInfo->iTop; i<last; i++, pOp++){ - if( pOp->p1!=pLevel->iTabCur ) continue; - if( pOp->opcode==OP_Column ){ - pOp->p1 = pLevel->iIdxCur; - for(j=0; j<pIdx->nColumn; j++){ - if( pOp->p2==pIdx->aiColumn[j] ){ - pOp->p2 = j; - break; - } - } - }else if( pOp->opcode==OP_Rowid ){ - pOp->p1 = pLevel->iIdxCur; - pOp->opcode = OP_IdxRowid; - }else if( pOp->opcode==OP_NullRow ){ - pOp->opcode = OP_Noop; - } - } - } - } - - /* Final cleanup - */ - sqliteFree(pWInfo); - return; -} |